How can a contact be Unsubscribed but still be able to open emails on another device?

I was researching a member's complaint that she did not receive a recent election survey. I saw that she had Unsubscribed, which she does not remember doing, but when I looked at her engagement history, it appears that after Unsubscribing, she continued to receive and be able to open emails on other device https://files.constantcontact.com/daef8eb8001/df8ea652-a84a-4592-831c-768bb77632ee.pdf 

How is that possible?

Madeleine Crouch for American Viola Society

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